6.29.6 Formatter Objects
Formatters have the following attributes and methods. They are
responsible for converting a LogRecord to (usually) a string
which can be interpreted by either a human or an external system. The
base
Formatter allows a formatting string to be specified. If none is
supplied, the default value of '%(message)s' is used.
A Formatter can be initialized with a format string which makes use of knowledge of the LogRecord attributes - such as the default value mentioned above making use of the fact that the user's message and arguments are pre-formatted into a LogRecord's message attribute. This format string contains standard python %-style mapping keys. See section 2.3.6, ``String Formatting Operations,'' for more information on string formatting.
Currently, the useful mapping keys in a LogRecord are:
| Format | Description |
|---|---|
%(name)s |
Name of the logger (logging channel). |
%(levelno)s |
Numeric logging level for the message (DEBUG, INFO, WARNING, ERROR, CRITICAL). |
%(levelname)s |
Text logging level for the message
('DEBUG', 'INFO',
'WARNING', 'ERROR',
'CRITICAL'). |
%(pathname)s |
Full pathname of the source file where the logging call was issued (if available). |
%(filename)s |
Filename portion of pathname. |
%(module)s |
Module (name portion of filename). |
%(lineno)d |
Source line number where the logging call was issued (if available). |
%(created)f |
Time when the LogRecord was created (as returned by time.time()). |
%(asctime)s |
Human-readable time when the LogRecord was created. By default this is of the form ``2003-07-08 16:49:45,896'' (the numbers after the comma are millisecond portion of the time). |
%(msecs)d |
Millisecond portion of the time when the LogRecord was created. |
%(thread)d |
Thread ID (if available). |
%(threadName)s |
Thread name (if available). |
%(process)d |
Process ID (if available). |
%(message)s |
The logged message, computed as msg % args. |
-
Returns a new instance of the Formatter class. The
instance is initialized with a format string for the message as a whole,
as well as a format string for the date/time portion of a message. If
no fmt is specified,
'%(message)s'is used. If no datefmt is specified, the ISO8601 date format is used.
-
The record's attribute dictionary is used as the operand to a
string formatting operation. Returns the resulting string.
Before formatting the dictionary, a couple of preparatory steps
are carried out. The message attribute of the record is computed
using msg % args. If the formatting string contains
'(asctime)', formatTime() is called to format the event time. If there is exception information, it is formatted using formatException() and appended to the message.
- This method should be called from format() by a formatter which wants to make use of a formatted time. This method can be overridden in formatters to provide for any specific requirement, but the basic behavior is as follows: if datefmt (a string) is specified, it is used with time.strftime() to format the creation time of the record. Otherwise, the ISO8601 format is used. The resulting string is returned.
- Formats the specified exception information (a standard exception tuple as returned by sys.exc_info()) as a string. This default implementation just uses traceback.print_exception(). The resulting string is returned.
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Release 2.4.4c1, documentation updated on 11 October 2006.